Knife-sharpening mechanism for cutting machines



Dec. 19, 1939. F. J. CLARK 2,133,786

KNIFE-SHARPENING MECHANISM FQR CUTTING MACHINES v Filed May 9, 1958 2 Sheets-Sheet 1 TILT lNl/E/VTO/Q.

W w, MViZ/mQ Dec. 19, 1939. F. J. CLARK KNIFE-SHARPENING MECHANISM FOR CUTTING MACHINES Filed May 9, 1938 2 Sheets-Sheet 2 9 25mm A TTO/Q/VEXS.

Patented Dec. 19, 1939 UNITED STATES KNIFE-SHARPENIN G MECHANISM FOR OUT- TIN G MACHINES Frederick J. Clark, Buffalo, N. Y., assignor to Eastman Machine Company, Buffalo, N. Y.

Application May 9, 1938, Serial No. 206,752

11 Claims.

This invention relates more particularly to improvements in knife-sharpening mechanisms for cutting machines of the type, commonly used for cutting cloth and other sheetmaterials, compris- 5 ing an upright, vertically reciprocating knife with a substantially vertical cutting edge which can be caused to follow a desired pattern or line of cut in a lay of cloth or other material by appropziately moving and guiding the machine about 10 upon the supporting table for the material; and one purpose of my invention is to provide drive mechanism of improved construction for the knife sharpening means of such machines.

Other objects of the invention are to provide 15 an efficient drive mechanism of novel construction for abrasive band or belt knife-sharpening means of the character disclosed in application for United States Letters Patent, Serial Number 198,298, filed March 26, 1938, by myself and Carl 2 F. Hilgeman; also to provide novel drive mechanism of exceedingly simple, strong and durable construction for the knife-sharpening means of cutting machines of the type mentioned; and also to provide knife-sharpening mechanism for cutting machines having the other features of im- 2 provement and advantage hereinafter described and set forth in the claims.

In the accompanying drawings: Fig. 1 is a side elevation, partly in vertical section, of an upright, reciprocating knife cutting machine, equipped with knife sharpening mechnism embodying my invention.

Fig. 2 is a fragmentary front elevation thereof and, like Fig. 1, shows the upper. inoperative posi- 35 tion of the grinding means.

Fig. 3 is a transverse, sectional elevation thereof on line 33, Fig. 1, and showing by dotted lines the operative position of the drive mechanism for the grinding means.

Fig. 4 is a sectional plan view of the sharpening means on line 4-4, Fig. 3.

Except with respect to the knife-sharpening mechanism and associated parts, this invention is not concerned with the construction of the cutting machine, and it may be of the construction illustrated in the drawings or of other suitable construction. As herein disclosed, the machine comprises the usual base l5 adapted to rest and be moved about upon the table or supporting surface for the material to be cut, an upright slender standard l6 which is rigid with and rises from the base and supports a stationary frame I? housing an electric or other motor at l8, which reciprocates the vertical knife E9 in a guide slot 55 in the front of the standard through drive con nections comprising a slide to which the knife is secured at its upper end and which is connected by a pitman 2! to the crank pin of a crank wheel 22 on the front end of the horizontal rotary 60" shaftof the motor. 23 indicates the usual presser foot fixed to the lower end of a rod 24 which extends vertically in front of the knife l9, forming a guard therefor, and is adjustable vertically in a suitable guide 25 to support the presser foot at different elevations suited to different lays of material to be cut. The rear end of the presser foot shown is bifurcated and straddles the front edge portion of the standard to assist inpreventing lateral deflection of the guard rod. The guard rod may be releasably held in different adjustments, as by a dog 26on the front end of a release lever 21 and pressed into engagement with the toothed side of the guard rod by a' spring 28. The lever 2! shown is pivoted at one side of the machine in a position to be readily actuated for moving the dog to release the guard rod by a finger of the operators hand which grasps the handle 29 of the machine.

In the preferred embodiment of my invention illustrated in the drawings, flexible, abrasive band knife-grinding means are employed, preferably comprising flexible belts orstrips 30 and 3|, having grinding surfaces of carborundum or other suitable abrasive material disposed at opposite sides of the knife in such a way that they can be caused to travel in sharpening contact with opposite sides of the front edge portion of the knife. Said grinding means, like the similar means shown in the aforesaid application, may be power driven, for example, as shown, by the knife-operating motor of the machine, so that the band stretches or portions of the belts which contact with the knife, travel athigh speed forwardly past the latter, and they are mounted on a grinder carriage or support .32 arranged for movement up and down along the knife to enable the sharpening of the knife throughout its full cutting length.

Said grinding means, together with the drive means therefor, and other operative parts of the sharpening mechanism are preferably mounted on a frame part or housing 33 which is stationarily but removably secured at the front of the machine, as by screws 34 screwed into the front of the stationary frame I? so that the sharpening mechanism may be applied to and removed as aunit from the machine. The housing 33 shown also serves as a cover for the crank wheel 22 and other parts of the knife-operating mechanism.

The improved drive mechanism for the knifegrinding means is preferably constructed as follows:

35 and 36 represent two vertical shafts arranged in front of the knife and parallel therewith, a'nd preferably at opposite sides of the plane of the knife, to rotate and slide axially of themselves in suitable bearings 3'! and 31a in the housing 33. These shafts extend downwardly out of the lower end of the housing with their lower portions journalled and held from endwise movement in suitable bearings in the grinder carriage 32 so that the shafts move up and down with the carriage. Openings 38 in the upper end of the housing 33 make it possible for the upper ends of the shafts to extend therethrough above the housing, thereby enabling shafts to be employed which are long enough to permit the necessary vertical travel of the grinder carriage for sharpening a knife of the maximum length without increasing the height of the housing. The shafts 35 and 35 are rotated in opposite directions by a gear train comprising intermeshing pinions 39 and MB which are held from endwise movement in a chamber M in the lower portion of the housing 33, and to which the shafts are connected to rotate with the pinions to slide axially therethrough, as by keys projecting from the pinions into longitudinal keyways 42 in the shafts. Belt pulleys t5 and 46 keyed or otherwise fixed directly on the lower ends of shafts 35 and constitute supporting and drive pulleys for the knife-sharpening band-means or belts 30 and 3!.

Preferably, the pinions 39 and it) are spiral toothed pinions, and one of them, as 39, meshes with and is driven by a spiral pinion 47 which is rotated by a motor-driven belt drive mechanism. As shown, the pinion S7 and a pulley i8 are formed or secured on a hub or sleeve 49 which is mounted to rotate on a horizontal stud axle 5B stationarily secured at its front end in the front wall of the housing 33 and projecting rearwardly in the housing. The pulley is connected by a belt 52 with a driving pulley 53 connected to a wheel 56 which is movably mounted to adapt it to be shifted into and out of driving engagement with a motor-driven wheel. In theillustrated embodiment of the invention, the crank wheel :22 on the front end of the horizontal rotary shaft of the knife-operating motor is utilized as this drive wheel, and for this purpose the crank wheel is preferably provided with a tire or band 55 of suitable friction material adapted to drive the wheel 55 by frictional contact therewith. The driving pulley 53 and wheel 55, as shown, are formed on a connecting hub or sleeve which is journalled on a stud axle 56 secured to an up wardly projecting arm of a supporting lever 51 which is suitably fulcrumed on a pivot bolt 58 secured to front wall of the housing 33. The axle 55 is preferably adjustably secured in an elongated slot 55a in the lever 5'? to enable the driving pulley 53 to be adjusted toward or from the belt pulley d8, as may be necessary, to properly tension the belt 52.

Driving engagement of the wheel 55 with the drive wheel 22 may be effected by suitable means, such as a coil spring 59 confined in a socket 59a formed in the housing 33 with the outer end of the spring pressing against the upwardly projecting arm of the lever ill in a direction to hold the wheel 54 in contact with the drive wheel.

Disengagement of the wheel 56 from the drive whee1 22 for stopping the grinding means is preferably effected through movement of the grinder carriage to an upper, inoperative position, for which purpose a vertical push rod Gil is shown, arranged to slide lengthwise in a suitable guide bearing 58a in the housing 33, with its lower end arranged to be engaged by the carriage 32 and its upper end engaging the outer end of a lateral arm of the lever 5?. When sharpening the knife, the grinder carriage 32 will be spaced downwardly away from the lower end of the housing and the spring 59 will hold the Wheel 5-2 in engagement with the drive wheel 22, and hold the lower end of the push rod 56 projecting below the bottom of housing 33. The drive mechanism described will then rotate the belt pulleys 45, 55, and the abrasive belts 36, Si for sharpening the knife. When the sharpening of the knife is completed, the grinder carriage is pushed up to its highest, inoperative position, and the carriage will push up the rod iii! and swing the lever 51 so as to shift the wheel 5-! out of driving engagement with the drive wheel 22 and stop the grinding means.

The knife-sharpening belts 35 and 3! are shown, as in the aforesaid application, passing around the drive pulleys d5, 65, and two idler pulleys ill journalled on spring-pressed slides 54 which are movable toward and from the drive pulleys on fixed legs 53 projecting rearwardly from the grinder carriage 32 and straddling the knife standard. These movable idler pulleys maintain the belts under suitable tension and allow ready removal and renewal of the belts. Each idler pulley slide preferably consists, as best shown in Figs. 1 and 4, of a plate which extends across one face of its supporting leg 63 and has side walls t da with inwardly projecting flanges which embrace the opposite side edges of the leg to slidably retain the slide on the leg, and a transverse Wall 6th against which the spring t ic acts to press the slide and its idler pulley rearwardly for holding the sharpening belt under proper tension. This slide, which can be made from a single plate bent into the form shown, provides a desirable adjustable idler pulley mounting of exceedingly simple and inexpensive construction. Also, as shown in said application, the two sharpening belts, which are disposed at different levels, are yieldingly pressed into sharpening contact with the edge portion of the knife by the spring-pressed fingers 55, which are pivoted on the carriage legs, and are so shaped that they will hold those portions of the belts which contact the knife, at the requisite converging inclinations to insure the grinding of wide, thin, bevelled edges on the longitudinal and bottom edges on the knife, which edges will be very sharp or keen and will remain so for the maximum time.

The parallel sliding shafts 35 and 36, which are guided vertically in their hearings in the housing, act to guide the grinder carriage 32 to cause it to move up and down parallel with the knife edge, and prevent horizontal deflection or twisting of the carriage, thus providing desirable guide means therefor. Fig. 4 shows a spring-pressed guide block ti on the carriage with a slotted end yieldingly and slidably engaging the rear edge of the standard and supplementing the carriageguiding action of the parallel sliding shafts 35 and 56.

The described drive mechanism drives the grinding means or belts rapidly and positively and, the belts while running, may be moved up and down along the edge of the knife for sharpening its longitudinal edge throughout its effective length and also its bottom end or point, by any suitable means adapted to move the grinder carriage up and down. Preferably, the carriage is provided for this purpose with a forwardly pro- ,iecting handle 13 in the form of a stud fixed to the front end of the carriage 32 and adapted to be grasped by the hand.

In the normal operation of the machine for cutting material, the grinder carriage with its grinding means or belts is held in its uppermost position, shown in Fig. 1, where it is out of the way and does not interfere with the cutting operation of the knife nor obstruct the view of the operator in manipulating and guiding the machine so as to cause the cutting edge of the knife to properly follow the pattern or required line of cut. The grinder carriage is releasably held in this upper, inoperative position and the wheel 54 held out of engagement with the drive wheel 22 to prevent driving the grinding means, preferably by a cam latch 15, such as shown in the aforesaid application, and which is in the form of a lever pivoted on the carriage handle stud 13. This latch has a laterally extending cam edge 18 which, when the grinder carriage has been raised nearly to its uppermost position, is adapted to be swung into engagement with a forwardly projecting, fixed stud 79' on the housing 33, and by pressure of the latch, acts on the stud to cam ,the grinder carriage up to and releasably hold it in its uppermost, inoperative position.

The final upward movement of the grinder carriage by the cam latch operates through the push rod 6!), as before explained, to disengage the wheel 5 from the crank wheel 22 and throw the drive mechanism for the grinding means out of action. When the sharpening mechanism is in use, the grinder carriage is below said uppermost inoperative position, and the lower end of the push rod 59 projects below the bottom of the housing 33. In camming the grinder carriage up to its inoperative position by the latch T5, the carriage engages the projecting lower end of the push rod 60 and lifts the rod, thus swinging lever 51 and shifting the wheel 54 out of driving engagement with the crank wheel, thus stopping the grinding means.

When the knife requires sharpening, it is only necessary to release and lower presser foot to its lowest position, then release the latch 15 and move the grinder carriage down and up along the reciprocating knife by means of the handle stud 73. Only one or two down and up movements of the grinding means is usually necessar and at the end of the last up movement, the grinder carriage is latched in its inoperative position, as explained, and the machine is ready to continue its cutting.

The described drive mechanism for the grinding means is composed of the minimum number of parts of simple construction, and readily fabricated. It provides an efiicient and desirable drive of sturdy and durable construction, not likely to get out of order or cause trouble and annoyance.

I claim as my invention:

1. In a cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially in the lengthwise direction of said edge, of knife-grinding flexible abrasive band-means arranged to contact opposite sides of the edge portion of the knife, a carriage supporting said grinding means, means for moving said carriage and grinding means lengthwise along the knife edge, two laterally spaced apart shafts extending from said carriage upwardly parallel with the knife edge and movable up and down with said carriage, supporting and driving pulleys for said band-means fixed directly on said shafts, a gear train comprising pinions to each of which one of said shafts is slidably connected to rotate with and move axially of said pinion, a motor, and a belt drive mechanism operatively connecting said motor with said gear train for rotating said shafts.

2. In a cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially in the lengthwise direction of said edge, of knife-grind-u ing flexible abrasive band-means arranged to contact opposite sides of the edge portion of the knife, a carriage supporting said grinding means, means for moving said carriage and grinding means lengthwise along the knife edge, two laterally spaced apart shafts extending from said carriage upwardly parallel with the knife edge and movable up and down with said carriage,

supporting and driving pulleys for said bandmeans fixed directly on said shafts, a gear train comprising pinions to each of which one of said shafts is slidably connected to rotate with and move axially of said pinion, a motor, and belt drive mechanism for said gear train including a driving wheel movably supported and shiftable into and out of driving connection with said motor.

3. Ina cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially in the lengthwise direction of said edge, of knife-grinding flexible abrasive band-means arranged to contact opposite sides of the edge portion of the knife, a carriage supporting said grinding means, means for moving said carriage and grinding means lengthwise along the knife edge, two laterally spaced apart shafts extending from said carriage upwardly parallel with the knife edge and movable up and down with said carriage, supporting and driving pulleys for said bandmeans fixed directly on said shafts, a gear train comprising pinions to each of which one of said shafts is slidably connected to rotate with and move axially of said pinion, a motor, and belt drive mechanism for said gear train, comprising a pulley connected with a gear of said train, a driving pulley, a, belt connecting said pulleys, a wheel connected to said driving pulley, and means for supporting and shifting said wheel into and out of driving connection with'said motor.

4.'In a cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially in the lengthwise direction of said edge, of knife-grinding flexible abrasive band-means arranged to contact opposite sides of the edge portion of the knife, a carriage supporting said grinding means, means for moving said carriage and grinding means lengthwise along the knife edge, two laterally spaced apart shafts extending from said carriage upwardly parallel with the knife edge and movable up and down with said carriage, supporting and driving pulleys for said. band-means fixed directly on said shafts, a gear train comprising pinions to which said shafts are connected to rotate with and move axially of said pinions, a motor, and belt drive mechanism for said gear train comprising a pulley connected with a gear of said train, a second pulley arranged above said first pulley, a belt connecting said pulleys, and a Wheel secured to said second pulley, a pivoted lever supporting said second pulley and wheel, and means for moving said lever to shift said wheel into and out of driving connection with said motor.

5. In a cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially inthe lengthwise direction of said edge, of knife-grinding flexible abrasive band-means arranged to contact opposite sides of the edge portion of the knife, a carriage supporting said grinding means, means for moving said carriage and grinding means lengthwise along the knife edge, two laterally spaced apart shafts extending from said carriage upwardly parallel with the knife edge and movable up and down with said carriage, supporting and driving pulleys for said bandmeans fixed directly on said shafts, a gear train comprising pinions to each of which one of said shafts is slidably connected to rotate with and move axially of said pinion, a motor, belt drive mechanism operatively connecting said motor with said gear train and including a driving wheel shiftable into and out of driving connection with said motor, and means actuated by movement of said grinder carriage to an inoperative position for shifting said wheel out of driving connection with said motor.

6. In a cutting machine, the combination with a knife which has a substantially upright cutting edge and is reciprocated substantially in the lengthwise direction of said edge, of knifegrinding flexible abrasive band-means arranged to contact opposite sides of the edge portion of the knife, a carriage supporting said grinding means, means for moving said carriage and grinding means lengthwise along the knife edge, two laterally spaced apart shafts extending from said carriage upwardly parallel with the knife edge and movable up and down with said carriage, supporting and driving pulleys for said band-means fixed directly on said shafts, a gear train comprising pinions to one of which each of said shafts is slic'lably connected to rotate with and move axially of said pinion, a motor, belt drive mechanism operatively connecting said motor with said gear train including a driving wheel, a spring for shifting said driving wheel into driving connection with the motor, and means actuated by movement of said grinder carriage to an inoperative position for shifting said driving wheel out of driving connection with said motor. l

7. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of said edge, of knifegrinding elements disposed to contact opposite sides of the edge portion of the knife, a supporting carriage for said elements movable to carry said elements lengthwise along the knife edge, and drive mechanism for said elements comprising two laterally spaced apart shafts extending upwardly from said carriage parallel with said knife edge and movable up and down with said carriage, a drive connection from each shaft to one of said grinding elements, a motor, a gear train located below said motor and above said carriage and comprising pinions to each of which one of said shafts is slidably connected to rotate with and move axially of said pinion, and belt drive mechanism operatively connecting said motor with said gear train for rotating said shafts.

8. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of said edge, of knifegrinding elements disposed to contact opposite sides of the edge portion of the knife, a supporting carriage for said elements movable to carry said elements lengthwise along the knife edge, and drive mechanism for said elements comprising two laterally spaced apart shafts extending upwardly from said carriage parallel with said knife edge andmovable up and down with said carriage, a drive connection from each shaft to one of said grinding elements, a gear train comprising pinions to each of which one of said shafts is connected to rotate with and move axially of said pinion, a motor, belt drive mechanism comprising a pulley connected with a gear of said train, a second pulley arranged above said first pulley, a belt connecting said pulleys, and a wheel secured to said second pulley, and a support for said second pulley and wheel movable to shift said wheel into and out of driving engagement with said motor.

9. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of said edge, of knifegrinding elements disposed to contact opposite sides of the edge portion of the knife, a supporting carriage for said elements movable to carry said elements lengthwise along the knife edge, and drive mechanism for said elements comprising two laterally spaced apart shafts extending upwardly from said carriage parallel with said knife edge and movable up and down with said carriage, a drive connection from each shaft to one of said grinding elements, a gear train comprising pinions to each of which one of said shafts is connected to rotate with and move axially of said pinion, a motor having a fore and aft extending horizontal rotary shaft, a drive Wheel on the front end of said motor shaft, a wheel shiftable parallel with its plane of rotation into and out of driving engagement with said drive wheel, a pulley secured to said shiftable wheel, a pulley connected with a gear of said train, and a belt connecting said pulleys.

10. In a cutting machine, the combination with a knife having a substantially upright cutting edge and which is reciprocated substantially in the lengthwise direction of said edge, of knifegrinding elements disposed to contact opposite sides of the edge portion of the knife, a supporting carriage for said elements movable to carry said elements lengthwise along the knife edge, and drive mechanism for said elements comprising two laterally spaced apart shafts extending upwardly from said carriage parallel with said knife edge and movable up and down with said carriage, a drive connection from each shaft to one of said grinding elements, a motor, a gear train located below said motor and above said carriage and comprising pinions to each of which one of said shafts is connected to rotate with and move axially of said pinion, belt drive mechanism for said gear train including a driving wheel shiftable into and out of driving engagement with said motor, and means actuated by movement of said grinder carriage to and from an inoperative position for shifting said driving wheel out of and into driving engagement with said motor.

11. In a cutting machine, the combination of a flexible sharpening belt for the machine knife, a supporting leg for said belt, a tightening pulley for said belt, and a slide carrying said pulley and comprising a plate extending across one face of said leg and having side walls with inwardly projecting flanges which slidably embrace the opposite edges of said leg, and a transverse wall, and a spring between and engaging said transverse wall and said leg and acting on the slide to hold said sharpening belt under tension.

FREDERICK J. CLARK. 

